New heights: Campus horticulturists make One Seed program their own
The Cockerells with red sunflowers, Boulder, CO, 1935.
Across campus, CU Boulder’s horticulturists have taken the University Libraries One Seed program and made it their own, experimenting with generations of red sunflowers while creating a living connection to a plant cultivated in Boulder more than a century ago.
One Seed is a community gardening project inspired by the work of Wilmatte Porter Cockerell, a high school biology teacher, and Theodore Dru Allison Cockerell, a CU Boulder professor. In 1910, Wilmatte Cockerell noticed a red sunflower growing near their Boulder home. The couple cultivated the unusual flower, and materials documenting their work are now preserved in the University Libraries archives as part of the T.D.A. Cockerell Collection.
More than a century later, campus horticulturists are continuing that experimentation. By saving seeds from plants with particular traits and growing them again, different teams are taking the sunflower in different directions: Main Campus horticulturists are selecting for deeper red flowers, East Campus horticulturists are pushing the plants to new heights, and in CU Boulder’s native areas, a handful of survivors could become the starting point for sunflowers better adapted to challenging growing conditions.
Going red on Main Campus
The story of how the red sunflowers were cultivated by the Cockerells was new to Christian Parker, Main Campus Horticulture and Weed Management Supervisor.
“There are so many nooks and crannies in history, interesting little local stories that are always fun to learn about,” said Parker. “But it is rare when it involves something in our gardening/horticulture world.”
Parker and the Outdoor Services Team were invited to Norlin’s Special Collections Reading Room by Abbey Lewis, STEM Engagement Librarian in the Learning & Engagement Department and creator of the One Seed program, to see archival materials connected to the sunflower and soon began growing the flowers themselves.
“Hearing their passion for this flower and its local history got us excited to help them add another chapter to this sunflower’s story,” Parker said. “Making our team, and this campus a part of its colorful life.”
At first, many of the sunflowers they grew weren't particularly red.
“The first year flowers were mostly yellow, with very little that came up red,” Parker said.
Genetics are the biggest factor for how red or yellow they will ultimately be. To encourage a deeper red color, they hand-pollinated some of the reddest flowers with one another, covered the flower heads with cheesecloth to prevent accidental pollination with yellow flowers and saved those seeds for the following year.
A cluster of red sunflowers growing near the Recreation Center.
“As a result of that one year’s efforts, we have added to the saturation of the red in the sunflowers, and now see many different hues of red sunflowers in all our plantings,” Parker said. “I’d say this year has been our most colorful display yet!”
For Parker, the flowers offer something different from much of the campus landscape.
“The sunflower is a bright ray of sunshine that suddenly appears as you round a corner on campus,” Parker said. “Even if it has not yet opened its flower when you first see it growing in a bed, chances are you are going by that spot every day in anticipation of its opening petals.”
Those flowers also create opportunities to share the history behind them. Parker frequently sees people stop to admire and photograph the sunflowers while she is working.
“Many times they will ask me what variety they are, which I always love when they do, as I get to explain not only the history of the flower, but the conservation efforts that the One Seed program is currently doing,” Parker said.
Going tall on East Campus
East Campus horticulturists saw a different possibility.
“The Main Campus team saw a flower and said ‘Let’s make it redder!’ We saw the same thing and said ‘Let’s make it taller!’,” said Charles Holstein, East Campus Horticulture Supervisor. “We actually have plans to cross pollinate theirs and ours, to try to grow some monster red sunflowers. It’s all a fun experiment.”
Near the south entrance of the ARC building, the East Campus team is growing Cockerell sunflowers alongside several other sunflower varieties. Some reached 11 feet this summer.
“A couple of years ago, we realized that we’d found a spot they really liked, and we embraced it,” Holstein said. “Sometimes you have to let the plants tell you where they’d like to live, and these sunflowers told us loudly and clearly that they wanted to be right here, reaching for the sun!”
Like their Main Campus counterparts, East Campus gardeners started saving seeds from plants exhibiting the characteristics they wanted.
“Each plant is an individual, and some are better suited to our conditions than others,” Holstein said. “When we saw the unusual height on these, we knew we needed to experiment and see what they’d do after a few more generations.”
Keeping towering sunflowers upright presents its own challenges. The gardeners overplant and later remove all but the heartiest seedlings. They prune flowers after they bloom to reduce weight and stake some of the largest plants. Eventually, they couldn't find stakes tall enough to support the flowers.
“Now we use the dried stalks of the previous year’s tallest sunflowers,” Holstein said.
The experimentation fits into a larger approach to the East Campus landscape—one Holstein describes as beautiful and curated while also sustainable and connected to the surrounding environment. The historical connection adds another dimension.
Joshua Hollingshead and Alex Hughes, Horticulturist in Outdoor Services, stand in front of East Campus sunflowers.
“It’s really fun to watch these grow and feel a connection to the people right here in Boulder that grew them and admired them a century ago.” Holstein said. “So much has changed since then, and it’s nice to remember that some things really haven’t—when you put a seed in the soil, give it water, and get to watch as it germinates and grows, you’re performing a ritual that so many generations of our ancestors would recognize immediately.”
Growing tougher sunflowers
For Joshua Hollingshead, CU Boulder Native Area Management Specialist, neither height nor color is the priority.
“At this point, I'm looking for a stronger sunflower above all else,” Hollingshead said.
Hollingshead manages native areas across Main, East and South campuses, working to eradicate noxious weeds, reestablish native plants that support wildlife and ultimately reduce the amount of water needed to maintain the landscape.
Growing sunflowers in those conditions hasn't been easy. After struggling to establish seeds directly in dry soil, Hollingshead's team tried a new approach this year. Seventy plants were started in a greenhouse, hardened off to acclimate them to hot, dry conditions and transplanted into an irrigated native area. Then a pump failed and limited the amount they could water.
“Of the 70 plants we put in, only three survived and are now flowering strong,” Hollingshead said. “It shows that even under favorable circumstances, establishing native plants in our native areas is genuinely difficult.”
But those three survivors could help determine what comes next. Hollingshead plans to collect their seeds, broadcast half directly in the area and start the other half in the greenhouse to compare how they perform.
While Main and East Campus horticulturists select for traits that stand out visually, Hollingshead is interested in plants capable of surviving the less controlled conditions of CU Boulder’s native areas.
Deep red sunflower in a native plants area of campus. Photo taken by Joshua Hollingshead.
“Flowers are often cross-bred purely for beauty, which works well in an irrigated bed where shade and sun can be controlled to benefit certain plants,” he said. “But most of our native areas on campus are open-space designs, which don't give weaker plants much of a chance to thrive.”
Establishing more flowering plants is part of Hollingshead's effort to create native landscapes that support wildlife while also changing perceptions of what a beautiful campus landscape can look like.
“I'd love to see our native areas full of all kinds of beautiful flowers,” Hollingshead said. “I want people to notice these areas more, and color is a great way to draw that attention.”
Those plants provide more than color. Hollingshead sees firsthand how insects and animals use them.
“Even when I find that a deer has eaten half of the few sunflowers I managed to establish, it's a reminder of just how much wildlife depends on these native plants—and how important they really are.”
One seed, many experiments
More than a century after the Cockerells experimented with a red sunflower in Boulder, experimentation with the flower continues across CU Boulder. Each group has taken the same seed and followed a different question. And in doing so, the horticulturists are extending a story that began locally more than 115 years ago—not simply preserving the history behind the red sunflower, but adding to it.
As Holstein put it, “I think that’s the beauty of horticulture and working with living things.”
For Hollingshead, the vision for where the experiment might ultimately lead is even simpler. Asked what he hopes CU Boulder’s native areas will look like several years from now, his answer was three words: “Full of color.”